For many thousands of years, the sea was considered a watery desert and it was believed the sea floor was a flat, lifeless plain. Some even imagined that there was no sea floor and the ocean was a bottomless abyss. But in the last 200 years a number of new technologies, and brave souls, have made it possible for humans to venture beneath the waves and find out exactly what is down there. From the earliest explorations on ships, to the newest, unmanned, remotely operated submersibles follow along as we chronicle the age of ocean exploration.